body{
    margin: 0;
    padding: 0;
}
ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: #333;
}

li {
    float: left;
}

li a {
    display: block;
    color: white;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
}

li a:hover {
    background-color: #111;
}
.sign-div{
    width: 100%;
    height: 100%;
    padding: 0px;
    text-align: center;
    /*flask中设置html背景图片必须放在static文件夹中*/
    background: url(../images/vaccine.jpg) no-repeat;
    position:absolute;
    background-size: cover;
    box-sizing: border-box;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%);
    overflow: hidden;
}
.sign-div h1{
    margin-top: 100px;
    color: #fff;
    font-size: 40px;
}

.sign-div input{
    display: block;
    padding: 20px 16px; /*{#框内内容和外边框的间距#}*/
    height: 44px;
    width: 200px;
    text-align: center;
    box-sizing: border-box;
    outline: none;
    border: none;
    position: absolute;
    margin:4px;
    font-family: "montserrat",sans-serif;
}
.sign-id{
    left: 50%;
    top: 49%;
    border-radius: 14px;
    background: rgba(255,255,255,5);
}

.sign-btn{
    left: 70%;
    top: 80%;
    text-align: center;
    margin-top: 50px;
    margin-bottom: 50px;
    background: rgba(100,149,237,.7);
    color: aliceblue;
    border-radius: 44px;
    cursor: pointer;
    transition: 0.8s;
}

.sign-btn:hover{
    transform:scale(0.96);
}
.sign-div a{
    text-decoration: none;
    color: #fff;
    font-family: "montserrat", sans-serif;
    font-size: 14px;
    padding: 10px;
    transition: 0.8s;
    display: block;
}
.sign-div a:hover{
    background: rgba(0,0,0,.3);
}
.sign-div label {

    text-align: left;
    color: black;
    font-size:30px;
    font-family: 宋体;
    font-weight: bold;
    width: 200px;
}

#loginDiv {
    width: 37%;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 300px;
    background-color: rgba(75, 81, 95, 0.3);
    box-shadow: 7px 7px 17px rgba(52, 56, 66, 0.5);
    border-radius: 5px;
}
.active {
    background-color: #4CAF50;
}